A basic process for the production of arylene sulfide polymers from polyhalo-substituted aromatic compounds by reaction with an alkali metal sulfide in a polar organic solvent is disclosed in U.S. Pat. No. 3,354,129. This patent also discloses that the molecular weight of the arylene sulfide polymers can be reduced by the use of monohalo-substituted aromatic compounds as chain terminating agents or by the use of an excess of one of the reactants in the polymerization reaction mixture such as p-dichlorobenzene. While such methods do provide means of reducing the molecular weight of arylene sulfide polymers produced according to the teachings of U.S. Pat. No. 3,354,129, other methods of obtaining reduced molecular weight arylene sulfide polymers are desired which do not suffer from the disadvantages of the increased cost of added reactant materials or the need for recovering and recycling excess reactant materials to the polymerization zone.
Arylene sulfide polymers can be characterized at least in part in terms of a melt flow rate. It is generally considered that a melt flow rate is inversely related to molecular weight for polymeric materials in general and for arylene sulfide polymers in particular. Extrusion rate, which is more specifically defined hereinafter, is a specific type of melt flow rate which is particularly useful for characterizing arylene sulfide polymers in the lower molecular weight range. Arylene sulfide polymers having a relatively high extrusion rate are desirable for a variety of applications especially in the field of encapsulation of electronic components. For example, U.S. Pat. Nos. 4,337,182 and 4,482,665 provide exemplary disclosures of compositions comprising arylene sulfide polymers which are employed in the encapsulation of electronic components.
It is therefore an object of this invention to provide a method for producing poly(arylene sulfide) having a high extrusion rate in a readily controllable manner. It is another object of this invention to provide a method for producing poly(arylene sulfide) having a high extrusion rate by adjustment of a reactant concentration in the polymerization reaction mixture. It is another object of this invention to provide a method for producing poly(arylene sulfide) having an extrusion rate of at least about 100 grams/10 minutes.